In recent years, there has been proposed a vehicle having a plurality of batteries mounted thereon, of which the rated voltages are different from one another. In such a vehicle, there has been a possibility that at the time of changing the power generation voltage of a generator, the drive torque of the generator changes, so vibration and/or noise may be generated. On the other hand, there has been proposed a technique in which a difference between the drive torque at the time of charging a low voltage battery and the drive torque at the time of charging a high voltage battery is caused to reduce by stopping the power generation operation of a generator intermittently at the time of charging the high voltage battery (for example, see a Patent Document 1).
In a Patent Document 2, there is described a technique in which in a vehicle having a low voltage battery and a high voltage battery mounted thereon, of which the rated voltages are different from each other, the low voltage battery and the high voltage battery are charged in an alternate manner.
In a Patent Document 3, there is described a technique in which in cases where an overvoltage occurs in any of a plurality of cells of a lithium-ion battery which is composed of the plurality of cells connected in series to one another, the charge voltage of the lithium-ion battery is made lower than a specified value.
In a Patent Document 4, there is described a technique in which at the time of regenerative braking of a hybrid vehicle which has an internal combustion engine and an electric motor mounted thereon as power sources, the surplus electric power which can not be charged to a battery is selectively supplied to a plurality of electric loads.
In a Patent Document 5, there is described a technique in which in a vehicle provided with a changeover switch which is adapted to be switched over so as to distribute an output of a generator between a storage battery of a low voltage system and an electric load of a high voltage system, the output voltage of the generator is once made lower at the time when the changeover switch is switched over.